package com.example.utils;

import lombok.extern.slf4j.Slf4j;
import org.bouncycastle.asn1.gm.GMNamedCurves;
import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.engines.SM2Engine;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.crypto.signers.SM2Signer;
import org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPrivateKey;
import org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPublicKey;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.util.encoders.Hex;

import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.spec.ECGenParameterSpec;
import java.util.Base64;

/**
 * @Description : SM2加解密工具
 * @Author : ZYX
 * @Date : 2024/1/14 19:17
 * @Version : 1.0
 **/
@Slf4j
public class SM2Util {

    private static final String EC = "EC";

    /**
     * 生成 SM2 公私钥对
     *
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidAlgorithmParameterException
     */
    public static KeyPair geneSM2KeyPair() throws NoSuchAlgorithmException, InvalidAlgorithmParameterException {
        final ECGenParameterSpec sm2Spec = new ECGenParameterSpec("sm2p256v1");
        // 获取一个椭圆曲线类型的密钥对生成器
        final KeyPairGenerator kpg = KeyPairGenerator.getInstance(EC, new BouncyCastleProvider());
        // 产生随机数
        SecureRandom secureRandom = new SecureRandom();
        // 使用SM2参数初始化生成器
        kpg.initialize(sm2Spec, secureRandom);
        // 获取密钥对
        KeyPair keyPair = kpg.generateKeyPair();
        return keyPair;
    }

    /**
     * 生产hex秘钥对
     */
    public static void geneSM2HexKeyPair(){
        try {
            KeyPair keyPair = geneSM2KeyPair();
            PrivateKey privateKey = keyPair.getPrivate();
            PublicKey publicKey = keyPair.getPublic();
            log.info("========  EC X Y keyPair    ========");
            log.info("privateKey:{}",privateKey);
            log.info("publicKey:{}",publicKey);
            log.info("========  hex keyPair       ========");
            log.info("hex priKey: {}", getPriKeyHexString(privateKey));
            log.info("hex pubKey: {}", getPubKeyHexString(publicKey));
            log.info("========  base64 keyPair    ========");
            log.info("base64 priKey: {}", new String(Base64.getEncoder().encode(privateKey.getEncoded())));
            log.info("base64 pubKey: {}", new String(Base64.getEncoder().encode(publicKey.getEncoded())));
            log.info("========  generate finished ========");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 获取私钥（16进制字符串，头部不带00长度共64）
     *
     * @param privateKey 私钥PrivateKey型
     * @return
     */
    public static String getPriKeyHexString(PrivateKey privateKey) {
        // OK
        BCECPrivateKey key = (BCECPrivateKey) privateKey;
        BigInteger intPrivateKey = key.getD();
        String priKeyHexString = intPrivateKey.toString(16);
        return priKeyHexString;
    }
    /**
     * 获取私钥 base64字符串
     *
     * @param privateKey 私钥PrivateKey型
     * @return
     */
    public static String getPriKeyBase64String(PrivateKey privateKey) {
        return new String(Base64.getEncoder().encode(privateKey.getEncoded()));
    }

    /**
     * 获取公钥（16进制字符串，头部带04长度共130）
     *
     * @param publicKey 公钥PublicKey型
     * @return
     */
    public static String getPubKeyHexString(PublicKey publicKey) {
        BCECPublicKey key = (BCECPublicKey) publicKey;
        return Hex.toHexString(key.getQ().getEncoded(false));
    }
    /**
     * 获取公钥 base64字符串
     *
     * @param publicKey 公钥PublicKey型
     * @return
     */
    public static String getPubKeyBase64String(PublicKey publicKey) {
        return new String(Base64.getEncoder().encode(publicKey.getEncoded()));
    }

    /**
     * SM2加密算法
     *
     * @param publicKey 公钥
     * @param data      明文数据
     * @return
     */
    public static String encrypt(String data, PublicKey publicKey) {
        return encrypt(data.getBytes(StandardCharsets.UTF_8), publicKey);
    }

    public static String encrypt(byte[] data, PublicKey publicKey) {
        BCECPublicKey key = (BCECPublicKey) publicKey;
        return encrypt(data, Hex.toHexString(key.getQ().getEncoded(false)));
    }

    public static String encrypt(String data, String pubKeyHexString) {
        return encrypt(data.getBytes(StandardCharsets.UTF_8), pubKeyHexString);
    }

    /**
     * SM2加密算法
     *
     * @param pubKeyHexString 公钥（16进制字符串）
     * @param data            明文数据
     * @return hex字符串
     */
    public static String encrypt(byte[] data, String pubKeyHexString) {
        // 获取一条SM2曲线参数
        X9ECParameters sm2ECParameters = GMNamedCurves.getByName("sm2p256v1");
        // 构造ECC算法参数，曲线方程、椭圆曲线G点、大整数N
        ECDomainParameters domainParameters = new ECDomainParameters(sm2ECParameters.getCurve(), sm2ECParameters.getG(), sm2ECParameters.getN());
        //提取公钥点
        ECPoint pukPoint = sm2ECParameters.getCurve().decodePoint(Hex.decode(pubKeyHexString));
        // 公钥前面的02或者03表示是压缩公钥，04表示未压缩公钥, 04的时候，可以去掉前面的04
        ECPublicKeyParameters publicKeyParameters = new ECPublicKeyParameters(pukPoint, domainParameters);

        SM2Engine sm2Engine = new SM2Engine(SM2Engine.Mode.C1C3C2);
        // 设置sm2为加密模式
        sm2Engine.init(true, new ParametersWithRandom(publicKeyParameters, new SecureRandom()));

        byte[] arrayOfBytes = null;
        try {
            arrayOfBytes = sm2Engine.processBlock(data, 0, data.length);
        } catch (Exception e) {
            log.error("SM2加密时出现异常" + e.getMessage());
        }
        return Hex.toHexString(arrayOfBytes);

    }

    /**
     * SM2解密算法
     * @param cipherData    hex格式密文
     * @param privateKey    密钥PrivateKey型
     * @return              明文
     */
    public static String decrypt(String cipherData, PrivateKey privateKey) {
        return decrypt(Hex.decode(cipherData), privateKey);
    }

    public static String decrypt(byte[] cipherData, PrivateKey privateKey) {
        BCECPrivateKey key = (BCECPrivateKey) privateKey;
        return decrypt(cipherData, Hex.toHexString(key.getD().toByteArray()));
    }

    public static String decrypt(String cipherData, String priKeyHexString) {
        // 使用BC库加解密时密文以04开头，传入的密文前面没有04则补上
        if (!cipherData.startsWith("04")) {
            cipherData = "04" + cipherData;
        }
        return decrypt(Hex.decode(cipherData), priKeyHexString);
    }

    /**
     * SM2解密算法
     *
     * @param cipherData      密文数据
     * @param priKeyHexString 私钥（16进制字符串）
     * @return
     */
    public static String decrypt(byte[] cipherData, String priKeyHexString) {
        //获取一条SM2曲线参数
        X9ECParameters sm2ECParameters = GMNamedCurves.getByName("sm2p256v1");
        //构造domain参数
        ECDomainParameters domainParameters = new ECDomainParameters(sm2ECParameters.getCurve(), sm2ECParameters.getG(), sm2ECParameters.getN());

        BigInteger privateKeyD = new BigInteger(priKeyHexString, 16);
        ECPrivateKeyParameters privateKeyParameters = new ECPrivateKeyParameters(privateKeyD, domainParameters);

        SM2Engine sm2Engine = new SM2Engine(SM2Engine.Mode.C1C3C2);
        // 设置sm2为解密模式
        sm2Engine.init(false, privateKeyParameters);

        String result = "";
        try {
            byte[] arrayOfBytes = sm2Engine.processBlock(cipherData, 0, cipherData.length);
            return new String(arrayOfBytes);
        } catch (Exception e) {
            log.error("SM2解密时出现异常,{}" , e.getMessage());
        }
        return result;
    }

    /**
     * @param data
     * @param priKeyHexString hex私钥，长度64
     * @return hex格式签名值
     * @throws Exception
     */
    public static String sign(String data, String priKeyHexString) throws Exception {
        return sign(data.getBytes(StandardCharsets.UTF_8), priKeyHexString);
    }

    /**
     * 签名
     * @param data              原始数据，字节数组
     * @param priKeyHexString   hex私钥，64长度
     * @return                  Hex字符串
     * @throws Exception
     */
    public static String sign(byte[] data, String priKeyHexString) throws Exception {
        String signValue = null;
        SM2Signer signer = new SM2Signer();
        X9ECParameters sm2ECParameters = GMNamedCurves.getByName("sm2p256v1");
        //构造domain参数
        ECDomainParameters domainParameters = new ECDomainParameters(sm2ECParameters.getCurve(), sm2ECParameters.getG(), sm2ECParameters.getN());
        CipherParameters param = new ParametersWithRandom(new ECPrivateKeyParameters(new BigInteger(priKeyHexString, 16), domainParameters));
        signer.init(true, param);
        signer.update(data, 0, data.length);
        signValue = Hex.toHexString(signer.generateSignature());
        return signValue;
    }

    /**
     * 验签
     * @param data                  原始数据
     * @param signValue             原始签名值(hex型)
     * @param publicKeyHexString    hex130长度公钥
     * @return                      ture or false
     * @throws Exception
     */
    public static boolean verify(String data, String signValue, String publicKeyHexString) throws Exception {
        return verify(data.getBytes(StandardCharsets.UTF_8), Hex.decode(signValue), publicKeyHexString);
    }

    /**
     * 验签
     * @param data                  原始数据字节数组
     * @param sign                  字节数组()
     * @param publicKeyHexString    hex130长度公钥
     * @return                      true or false
     * @throws Exception
     */
    public static boolean verify(byte[] data, byte[] sign, String publicKeyHexString) throws Exception {
        SM2Signer signer = new SM2Signer();
        X9ECParameters sm2ECParameters = GMNamedCurves.getByName("sm2p256v1");
        //构造domain参数
        ECDomainParameters domainParameters = new ECDomainParameters(sm2ECParameters.getCurve(), sm2ECParameters.getG(), sm2ECParameters.getN());
        if (publicKeyHexString.length() == 128) {
            publicKeyHexString = "04" + publicKeyHexString;
        }
        ECPoint ecPoint = sm2ECParameters.getCurve().decodePoint(Hex.decode(publicKeyHexString));
        CipherParameters param = new ECPublicKeyParameters(ecPoint, domainParameters);
        signer.init(false, param);
        signer.update(data, 0, data.length);
        return signer.verifySignature(sign);
    }

}

